Scanning unit for an optical position measuring device

ABSTRACT

A scanning unit for an optical position measuring device that includes a detector system that has a first reference pulse signal detector region disposed along a measuring direction and a second reference pulse signal detector region disposed along the measuring direction. The relative disposition of the reference pulse signal detector regions in the measuring direction is selected as a function of the structuring of a reference marking field on a scale for generating a reference pulse signal. An incremental signal detector region is disposed along the measuring direction and between the first and second reference pulse signal detector regions to generate at least one incremental signal.

Applicants claim, under 35 U.S.C. §119, the benefit of priority of thefiling date of Aug. 7, 1997 of a German patent application Serial Number197 34 136.5, filed on the aforementioned date, the entire contents ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a scanning unit for an optical positionmeasuring device. The position measuring device furnishes not onlyperiodic incremental signals but also at least one reference pulsesignal at a defined relative position of a scale and a scanning unitthat is movable relative to the scale. To that end, at least onereference marking field is disposed on the scale, integrated into theincremental graduation track.

2. Description of the Related Art

Known optical position measuring devices, of the kind used for instancein machine tools to detect the relative position of the workpiece andthe tool, as a rule generate not only incremental signals with respectto the relative offset but also so-called reference pulse signals. Byway of the reference pulse signals, at one or more defined relativepositions of the parts movable relative to one another, an exactabsolute reference can be established for the position measurement. Togenerate the reference pulse signals, reference marking fields aredisposed at one or more positions on the scale of the respectiveposition measuring device. The scanning unit of such a positionmeasuring device offers the opportunity, at the relative position of thescale and scanning unit that is to be detected, of generating acorresponding reference pulse signal that is suitably processed in thedownstream evaluation device.

With respect to the disposition of reference marking fields on thescale, various possibilities now exist. For instance, it is known fromU.S. Pat. No. 4,263,506 to dispose the reference marking fields on thescale laterally adjacent to the incremental graduation track. Aproblematic aspect of such an arrangement, however, is that in the eventof a possible twisting of the scale and the scanning unit about an axisperpendicular to the plane of the scale, or scanning plane, the exact,positionally correct association of the reference pulse signal with adefined period of the incremental signals is no longer assured.

It is also possible for one or more reference marking fields to beintegrated directly into the incremental graduation track, as has beenproposed for instance by U.S. Pat. No. 3,985,448. The aforementioneddisadvantages that result particularly in the event of twisting of thescale and the scanning unit, can be avoided if the reference markingfields are disposed in the incremental graduation track. The opticalscanning of an incremental graduation track into a which a referencemarking field is also integrated is done in the aforementioned referencevia a scanning unit that on the one hand has a suitably embodied scannerplate with corresponding scanning graduations and on the other asuitable detector system. One problematic aspect among others inscanning and incremental graduation track embodied in this way andhaving at least one integrated reference marking field is that in theregion of the reference marking field, only a sharply impairedincremental signal is available.

To circumvent this problem would require a very long reference markingfield on the scale in the measuring direction. This in turn means abulky scanning unit.

Along with generating the incremental signals using a scanning unitwhich has not only the appropriate detector elements but also a scannerplate, scanning units are known that have a so-called structureddetector system. On the scanner, active detector regions are providedadjacent one another in the measuring direction on a semiconductorsubstrate, and they each generate certain signal components of thescanning signals. In such scanning units, a single component thus takeson the combined function of a scanning graduation and a detectorelement. In this respect, see European Patent Disclosure EP 518 620 A1.However, this reference does not disclose how, with such a detectorsystem, a reference marking field integrated directly into theincremental graduation track can be scanned, and in which theaforementioned problems with regard to the reduced incrementalgraduation track in the region of the reference marking fields aresharply reduced.

From German Patent Disclosure DE 195 12 258, a structured detectorsystem is known that is used to generate a reference pulse signal.However, once again the reference markings are disposed laterallyadjacent to the incremental graduation. Accordingly, the aforementionedproblems again occur if the scale and scanning unit twist about an axisor perpendicular to the plane of the scale, or scanning plane. Theembodiment of the detector system proposed in this reference is notsuited for scanning a reference marking that is integrated directly intothe incremental graduation track.

SUMMARY OF THE INVENTION

It is an object and advantage of the present application to disclose ascanning unit of compact structure for an optical position measuringdevice, which in scanning a scale generates not only incremental signalsbut also a reference pulse signal at least one defined position. Theinfluences of error on generating the reference pulse signal that resultfrom the aforementioned twisting of the scale and scanning unit areintended to be minimized, as is the vulnerability to any possiblecontamination of the scale. In the generation of the reference pulsesignal, the least possible interfering influence on the incrementalsignal is also desirable. Finally, furthermore, the phase relationshipof the reference pulse signal relative to the incremental signals shouldbe preserved even if the scale should possibly tip about an axis in theplane of the scale.

This object is attained by a scanning unit as defined by a scanning unitfor an optical position measuring device that includes a detector systemthat has a first reference pulse signal detector region disposed along ameasuring direction and a second reference pulse signal detector regiondisposed along the measuring direction. The relative disposition of thereference pulse signal detector regions in the measuring direction isselected as a function of the structuring of a reference marking fieldon a scale for generating a reference pulse signal. An incrementalsignal detector region is disposed along the measuring direction andbetween the first and second reference pulse signal detector regions togenerate at least one incremental signal.

The embodiment according to the present invention of the detector systemin the scanning unit now assures the desired insensitivity in the eventof possible twisting of the scale and scanning unit about an axisperpendicular to the measurement plane. The location of the referencepulse signal generated relative to the incremental signals does notchange even in such a case.

It is furthermore assured that even in the region of the referencemarking field, signal components from the detector system are availablefor generating at least incremental signal. In addition, the incrementalsignal is only slightly affected. In this way, appropriate precision forthe position determination is assured.

In an advantageous feature of the present invention, a scanning unit ofextremely compact structure can be attained because of the embodimentaccording to the present invention of the detector system.

In the aforementioned embodiment of the scanning unit of the presentinvention, a so-called single-field scanning can also be assured. Thismeans that all the phase-displaced signal components that contribute togenerating the various optical scanning signals originate in a singlegraduation period of the scale graduation. This assures increasedinsensitivity to contamination, for instance on the scale. The qualityof the various scanning signals is affected uniformly in each case byany possible contamination.

In addition, however, it is understood also to be possible, along withthe single-field scanning arrangement mentioned, to embody alternativescanning arrangements in accordance with the present invention, examplesbeing so-called quasi-single-field scanning, in which all thephase-displaced signal components originate from only a few graduationperiods within the scanned scale region, or so-called Vernier scanningarrangements with different graduation periods of the structuresprovided on the scale and the scanner, etc.

Another advantage of the embodiment according to the present inventionthat can be listed is that now even if the scale should tilt in theplane of the scale, the phase relationship between the reference pulsesignal generated and the incremental signals is preserved. This can beascribed to the fact both the incremental signals and the referencepulse signal result from the same scanned point on the scale.

Because it is possible to eliminate the periodic incremental signalcomponent in the reference pulse signal, an increased reliability ofdetection for the latter signal is also obtained. To that end, the mostvarious options are disclosed below.

The provisions according to the present invention can also be realizedin the most various optical position measuring devices. These includeboth systems that provide a collimating optical system in the light beampath and position measuring devices with so-called divergentillumination, that is, systems in which no collimating optics areprovided in the light beam path, and so forth.

Furthermore, it is understood that both linear and rotational positionmeasuring devices, as well as systems operated in incident light ortransmitted light, can be embodied according to the present inventionequally well.

Further advantages and details of the scanning unit of the presentinvention will become apparent from the ensuing description of aplurality of exemplary embodiments taken in conjunction with theaccompanying drawings.

Shown are:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, schematically shows an optical position measuring device havinga scale that is scanned by a scanning unit embodied according to thepresent invention;

FIG. 2a, schematically shows a first exemplary embodiment of a scanningunit according to the present invention in conjunction with a scaleoptically scanned by it, in which collimated lighting of the scale takesplace;

FIG. 2b, illustrates the phase-displaced incremental signals, as well asof the reference pulse signal that can be generated via a scanning unitof FIG. 2a;

FIG. 3a, schematically shows a second embodiment of the scanning unit ofthe present invention in conjunction with a scale scanned by it;

FIG. 3b, illustrates the phase-displaced incremental signals, as well asof the reference pulse signal that can be generated via a scanning unitof FIG. 3a;

FIG. 4a, schematically shows a third embodiment of the scanning unit ofthe present invention in conjunction with a scale scanned by it;

FIGS. 4b and 4 c, illustrate reference pulse signal components that aregenerated in the scanning unit of FIG. 4a;

FIG. 4d, illustrates a resultant reference pulse signal that isgenerated with the scanning unit of FIG. 4a, along with an associatedtrigger threshold;

FIG. 5, schematically shows a fourth embodiment of the scanning unit ofthe present invention in conjunction with a scale scanned by it;

FIG. 6, schematically shows a fifth embodiment of the scanning unit ofthe present invention;

FIGS. 7a-7 d, each a schematic illustration to explain further possibleways of embodying the scanning unit of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, an optical position measuring device is shown which includesa scanning unit 1 embodied according to the present invention. Inaddition to the scanning unit 1, the position measuring device includesa scale 2 that can be moved in the measuring direction x relative to thescanning unit 1. The scanning signals generated by the scanning unit 1upon the relative displacement with respect to the scale 2 are deliveredto the evaluation device 3 indicated, which further processes thesesignals in a known manner. As the scanning signals, both at least oneincremental signal and at least one reference pulse signal aregenerated. In one possible application of the position measuring device,with these signals the relative position of the workpiece and tool innumerically controlled machine tool are for instance determined. As theevaluation device 3, accordingly a known numerical machine toolcontroller is used, to which the position-dependent scanning signals ofthe position measuring device are supplied.

In the exemplary embodiment of FIG. 1, an optical position measuringdevice is shown that operates with transmitted light, although that isnot essential to the present invention. Naturally, an optical positionmeasuring device operated with incident light could equally well beembodied according to the present invention. In the transmitted lightvariant shown, the scanning unit 1 includes on the one hand a part onthe transmission side, which among other elements has a light source 4,including a collimator optical system 5 preceding the light source 4. Onthe other, in the part of the scanning unit 1 on the detector side, adetector system 6 is provided, with various detector regions whoselayout will be described in further detail hereinafter in conjunctionwith the other drawing figures. As already indicated, the parts on thetransmission and detector sides of the scanning unit 1 are movablerelative to the scale 2 in the measuring direction x.

In the embodiment shown, an incremental graduation 8 extending in themeasuring direction x is disposed on the scale 2 in an incrementalgraduation track 9, which when optically scanned in the relative motiongenerates incremental signals in a known way, preferably a pair ofincremental signals with a phase offset of 90°. To that end, the scale 2has incremental graduation subregions 8 a, 8 b, disposed in alternationwith the incremental graduation 8 in the track 9, and these subregionshave different optical properties; in the case of the transmitted lightversion, the incremental subregions 8 a, 8 b are embodied as opaque andtransparent, respectively, to the light wavelength used. In thealternative case of an incident light arrangement, an array ofincremental graduation subregions 8 a, 8 b would then be provided thatact in a reflecting and nonreflecting manner for the beams strikingthem, and so forth.

In the detail of the scale 2 shown, a reference marking field 7 can alsobe seen, which is integrated with the incremental graduation track 9 ofthe scale 2 and is used to establish an unequivocal absolute referenceat a determined relative position of the scale 2 and scanning unit 1. Anenlarged view of the reference marking field 7 is shown in the lowerpart of FIG. 2a. In the reference marking field 7, there is anarrangement of reference marking field subregions 7.1 to 7.13 in themeasuring direction x that differs from the strictly periodic orequidistant arrangement of incremental graduation subregions 8 a, 8 b inthe remainder of the incremental graduation track 9 of the scale 2.

Thus in the exemplary embodiment shown in accordance with FIG. 2a, anarrangement of a total of thirteen transparent and opaque referencemarking field subregions 7.1 to 7.13 in the reference marking field 7has been selected; so that the reference marking field 7 can beunambiguously distinguished from the incremental graduation 8 withstrictly periodically alternating transparent and opaque incrementalgraduation subregions 8 a, 8 b, certain reference marking fieldsubregions now embodied as opaque. In this way, finally an aperiodicarrangement of reference marking field subregions 7.1 to 7.13 withdifferent optical properties results. In the exemplary embodiment shown,to that end, the four reference marking field subregions 7.1, 7.5, 7.11and 7.13, which are located at places where actually a transparentsubregion for generating an incremental signal would be disposed, areembodied as opaque.

It is understood that a plurality of reference marking fields 7 can alsobe integrated at defined positions into the incremental graduation track9 of the scale 2. This may involve reference marking fields disposed ina so-called spacing-coded manner or equidistantly disposed referencemarking fields, and so forth. In addition, it is possible at any time toarrange a plurality of incremental graduation tracks, possibly withdifferent graduation periods, adjacent one another and parallel on thescale and to integrate one or more reference marking fields into each ofthese tracks, and so forth.

A first embodiment of the scanning unit 1 of the present invention willnow be described in conjunction with FIG. 2a. This figure, in its upperportion, shows a view of the detector plane of the detector system 6 ofFIG. 1 in conjunction with various signal processing building blocks.Below that, the incremental graduation track 9 of the scale 2 with thereference marking field 7 and the incremental graduation 8 bordering iton the left and right are shown enlarged.

To detect the beams arriving from the scale 2, in this exemplaryembodiment of the scanning unit of the present invention a plurality ofradiation-sensitive detector regions D100-D107 are provided on thedetector side; they are each embodied as a rectangle and are disposedwith their long sides adjacent one another in the measuring direction x.The various detector regions D100-D107, in the event of relative motionof the scale and the scanning unit, each generate signal components thatin the manner to be described below are utilized for generatingphase-offset incremental signals INC₀, INC₉₀ and to generate a referencepulse signal REF.

Each of the outer detector regions and the detector regions borderingthem, that is, D100, D101 and D106 and D107, of the detector system 60serve here to generate the reference pulse signal REF; these detectorregions will therefore hereinafter be called reference pulse signaldetector regions D100, D101, D106, D107. The detector regions D102,D103, D104 and D105 of the detector system 60 that are located betweenthe reference pulse signal detector regions D100, D101, D106, D107 areused conversely to generate the at least one incremental signal duringthe relative motion of the scale and the scanning unit; preferably,however, two incremental signals INC₀, INC₉₀ phase-offset by 90° aregenerated, as in the exemplary embodiment shown. These detector regionswill hereinafter be called incremental signal detector regionsD102-D105. The relative disposition of the four incremental signaldetector regions D102-D105 provided in this exemplary embodiment is madesuch that the incremental signal detector region D102 generates afractional incremental signal with the phase relationship of 0°, D103generates a fractional incremental signal with the phase relationship of180°, D104 generates a fractional incremental signal with the phaserelationship of 90°, and D105 generates a fractional incremental signalwith the phase relationship of 270°.

It should be noted in addition here that it is understood that someother relative disposition of the various detector regions can also beselected within the scope of the present invention. In that case,adjacent detector regions generate signals with different phaserelationships from the above example. It would also be conceivable toarrange the detector regions such that they generate signals with thephase relationships of 0°, 120°, 240°, and so forth.

The relative disposition of the reference pulse signal detector regionsD100, D101, D106, D107 within the detector system 60 is made accordingto the invention as a function of the selected structuring of thereference marking field 7 on the scale. For instance, in the exemplaryembodiment of FIG. 2a, an embodiment of the reference marking field 7 onthe scale has been selected such that unlike the periodic disposition oftransparent and opaque subregions 7.1 to 7.13 in the incrementalgraduation 8, individual reference marking field subregions 7.1, 7.5,7.11 and 7.13 are embodied as opaque. The four reference pulse signaldetector regions D100, D101, D106, D107 are now disposed in the detectorsystem 60 in a manner corresponding to these four reference markingfield subregions 7.1, 7.5, 7.11 and 7.13 on the scale. As soon as thedetector system 60 in measurement operation is located at thecorresponding null point or reference position in relation to the scale,the result is a drop in intensity of the reference pulse signal REF,which is utilized for the sake of precisely detecting the referenceposition x_(REF).

To generate the phase-displaced incremental signals INC₀, INC₉₀, theoutput signals of the incremental signal detector regions D102-D105 areinterconnected in the manner shown in pairs with the inputs ofdownstream subtractors DIF10, DIF20; that is, D102 and D103 areinterconnected via DIF20, and D103 and D104 are interconnected viaDIF10. At the outputs of the subtractors DIF10, DIF20, finally, the twoincremental signals INC₀ and INC₉₀, displaced by 90° and free of directcurrent components, are available for further processing.

In order, with the variant shown of the detector system 60, to generatethe desired reference pulse signal REF at the reference positionx_(REF), on the one hand the outputs of all the reference pulse signaldetector regions D100, D101, D106, D107 are interconnected. Theresultant signal is present at the first input of a further subtractorDIF30. The phase-displaced output signals of all the incremental signaldetector regions D102-D105 are also added together with the aid of asummation element SUM into a reference signal having a constant signallevel. The resultant reference signal is delivered to the second inputof the subtractor DIF30. After the difference between the two appliedsignals is found via the subtractor DIF30, the desired reference pulsesignal REF results.

For the sake of adaptation of the reference signal level to the outputsignals of the reference pulse signal detector regions D100, D101, D106,D107, which may become necessary, the amplifier element AMP shownupstream of the subtractor DIF30 in the example of FIG. 2a can be used,whose gain is selected accordingly.

Alternatively, for the sake of suitable adaptation of the various signallevels, it can also be provided that a corresponding offset beelectronically added to one of the two signals involved in thedifference forming.

The phase-displaced incremental signals INC₀, INC₉₀ generated by such adetector system 60, along with the reference pulse signal REF at thereference position x_(REF), are shown schematically in FIG. 2b. The dropin intensity of the reference pulse signal REF at the reference positionx_(REF) can be seen clearly here. Also clearly visible is the periodicsignal component that results with such an arrangement and that ismodulated to the reference pulse signal REF adjacent to the referenceposition x_(REF) and that can possibly lead to an impairment of thereliability of detection. In the view in FIG. 2b, this periodic signalcomponent is shown exaggerated; that is, it is understood that theperiodicity of this signal component corresponds to that of theincremental signals INC₀, INC₉₀. From the exemplary embodiments below,still other different possibilities for how this periodic signalcomponent in the reference pulse signal REF, which results from scanningof the incremental graduation, can be minimized or eliminated.

The first variant, explained in conjunction with FIG. 2a, of thescanning unit of the present invention could be simplified in a furtherembodiment in such a way that only two reference pulse signal detectorregions are provided, between which at least one incremental signaldetector region is disposed. However, for the sake of increasedinsensitivity to interference factors, an embodiment of the detectorsystem with a plurality of detector regions each for the incrementalsignals and the reference pulse signal—as shown in FIG. 2a—isadvantageous.

Also, advantageously adjacent to the left and right of the referencepulse signal detector regions, other detector regions for generatingincremental signals and reference pulse signal detector regions areprovided. In this way, the scanning surface area and thus theinsensitivity to contamination are increased. In particular, it isfavorable in this respect to select the sum of all the incrementalsignal detector regions as greater than the sum of the reference pulsesignal detector regions, since in this way the influence of thereference marking field on the incremental signals generated can beminimized. A second, improved embodiment of the scanning unit 1 of thepresent invention will now be described in conjunction with FIG. 3a. Theupper part thereof again shows a view of the detector plane of thedetector system 6 of FIG. 1, in conjunction with various signalprocessing building blocks. Below it, the incremental graduation track 9of the scale 2 with the reference marking field 7 and the incrementalgraduation 8 adjoining on the left and right are shown enlarged.

For detecting the beams arriving from the scale 2, in this exemplaryembodiment of the scanning unit of the present invention, with regard todetectors a so-called structured detector system 6 is now provided. Inthe embodiment shown, it comprises active, that is, radiation-sensitivedetector regions D1, D2, D3 . . . , D44, which each are in the form of anarrow strip and are disposed periodically and adjacent one another inthe measuring direction x. To that end, a suitable semiconductorsubstrate should for instance be structured such that on the substrate,a number of such radiation-sensitive detector regions D1-D44 results.The various active detector regions D1-D44, when there is relativemotion of the scale and the scanning unit, each generate signalcomponents that are utilized in the manner described below to generatephase-offset incremental signals INC₀, INC₉₀ and to generate a referencepulse signal REF.

The active detector regions D1-D44 of the detector system 6 in theexemplary embodiment shown have so-called single-field scanning at araster spacing r in the measuring direction x that is less than thegraduation period TP of the scanned incremental graduation 8 inaccordance with the definition in FIG. 3a. TP here means the sum of thewidth of one transparent and one opaque incremental graduation subregionand 8 a and 8 b respectively, in the measuring direction x. The rasterspacing r of the detector system is obtained as the sum of the width dof the inactive zones between the active detector regions and the widthb of the active detector regions, that is, r=d+b. In the embodimentshown, it is selected that r=TP/4, which is equivalent to a phasedisplacement of 90° of the signals of adjacent detector regions. Thelength of the active detector regions D1-D44 perpendicular to themeasuring direction x should be optimized as a function of theparticular optical configuration involved.

The relative disposition of the active detector regions D1-D44 in themeasuring direction x is consequently selected in this embodiment suchthat within one graduation period TP, respective active detector regionsD1-D44 and inactive detector regions are arranged in alternating groups.The spacing d of adjacent active detector regions D1-D44 and thus thewidth of the inactive zones is accordingly TP/8 in this exemplaryembodiment. Over the entire detector system 6 in the exemplaryembodiment shown, a total of 44 active detector regions D1-D44 aredistributed equidistantly in the measuring direction x in eleven groupsof four over eleven graduation periods TP.

The spaced-apart arrangement shown for the active detector regionsD1-D44 is no way essential to the present invention; that is, animmediately adjacent disposition of active detector regions with aspacing d=0 could also be provided. In such a case, an increased signalintensity would in particular have to be expected from the scanningsignals obtained from the various detector regions, because then noregions of the structured detector system 6 would fail to be involved ingenerating signals. Furthermore, it is understood that other relativearrangements of active detector regions can also be realized within thescope of the present invention, which will described in still furtherdetail in terms of other exemplary embodiments. For instance, it wouldbe possible to select the raster spacing as r=TP/3, which would resultin a phase displacement between the signals of adjacent detector regionsof 120°.

The arrangement shown in the example of FIG. 3a of active detectorregions D1-D44 means that the adjacent active detector regions, locatedwithin one graduation period TP, of one group of four, upon opticalscanning of the incremental graduation 8 and of the reference markingfield 7, generate four scanning signals, each phase-offset by 90°. Byway of the arrangement of detector regions as shown, a so-called“single-field scanning” of the scale is thus assured, in which all thesignal components for generating the incremental signals and thereference pulse signal each originate in only one graduation period ofthe scales scanned. Scanning in this way is especially advantageous withregard to the insensitivity to large-area contamination of the scale,since the phase-displaced signal components that contribute togenerating the scanning signals are all affected equally.

As already mentioned above, by the suitable choice of the location andsize of the detector regions, a so-called quasi-signa1-field scanningcould also be realized within the scope of the present invention, inwhich case the signal components used for generating signals originatein detector regions that extend over more than one graduation period inthe measuring direction, with adjacent detector regions each generatingsignal components with different phase relationships. The width b of thedetector regions is then b#TP/2, and the raster spacing r of adjacentdetector regions should preferably be selected using the equationr=(2l+1)*TP/4, where l=0, 1, 2 . . . . Selecting 1=0 represents thesigna1-field scanning mentioned. Depending on what value is selected for1, different phase relationships of the various adjacent detectorregions then result.

For instance, if l=1, the phase relationships are approximately 0°,270°, 180° and 90°, for each four adjacent detector regions.

As an alternative, it could also be selected that r=l*TP/3, in whichcase 1 is a whole number not divisible by 3, that is, l=1, 2, 4, 5, 7, .. . .

In the exemplary embodiment of FIG. 2a, of the total of eleven groups offour active detector regions D1-D44, some of these groups of four areutilized to generate the reference pulse signal REF; these groups offour will hereinafter be called reference pulse signal detector regionsG_(REF)n. The reference pulse signal detector regions G_(REF)n are thefourth, sixth, ninth and tenth groups of four G_(REF) 1, G_(REF) 2,G_(REF) 3, G_(REF) 4 from the left, which have the active detectorregions D13-D16, D21-D24, and D33-D40. As to the concrete processing ofthe output signals of the reference pulse signal detector regionsG_(REF)n, more details will provided hereinafter.

The remaining groups of four active detector regions are converselyutilized to generate the phase-offset incremental signals INC₀ andINC₉₀; these groups will hereinafter be called incremental signaldetector regions G_(INC)n. The incremental signal detector regionsG_(INC)n are, beginning at the left, the first through third groups offour G_(INC) 1-G_(INC) 3 having the detector regions D1-D12, the fifthgroup of four G_(INC) 4 having the detector regions D17-D20, the seventhand eighth groups of four G_(INC) 5, G_(INC) 6 having the detectorregions D25-D32, and the eleventh group of four G_(INC) 7 having thedetector regions D41-D44. With the exception of the first and eleventhincremental signal detector regions G_(INC) 1 and G_(INC) 7 at theperiphery, the active detector regions belonging to the incrementalsignal detector regions G_(INC)n are disposed between of the referencepulse signal detector regions.

The location of the reference pulse signal detector regions G_(REF)n,which in this exemplary embodiment comprise a plurality of groups offour active detector regions G_(REF) 1-G_(REF) 4 and are used togenerate the reference pulse signal REF, is according to the presentinvention again selected as a function of the structuring of thereference marking field 7 on the scale. In the exemplary embodimentshown with collimated lighting of the scale, the three-dimensionallocations of these reference pulse signal detector regions G_(REF)1-G_(REF) 4 in the detector system 6 corresponds to thethree-dimensional location of each two successive opaque referencemarking field subregions in the reference marking field 7 on the scale;that is, the location of the reference marking field subregions 7.1 and7.2, 7.4 and 7.5, 7.10 and 7.11, and 7.12 and 7.13. Thethree-dimensional location of the reference pulse signal detectorregions G_(REF)n used to generate the reference pulse signal is thusselected as a function of the three-dimensional location of the opaquereference marking field subregions 7.2, 7.5, 7.11 and 7.13 that disturbthe periodic scale structure.

The location of the reference pulse signal detector regions G_(REF) 1G_(REF) 4 utilized to generate the reference pulse signal REF isaccordingly selected, in the case of the collimated lighting, directlyas a function of the structure of the reference marking field 7 on thescale. As a result, the aperiodic structure of the reference markingfield 7 is reproduced in the detector plane by the selected activedetector regions of the reference pulse signal detector regions G_(REF)nfor detecting the reference pulse signal REF.

This exact reproduction of the structure of the reference marking fieldby means of the selection of the reference pulse signal detector regionsG_(REF)n used to form the reference pulse signal is, however, in no waycompulsory for the present invention. For instance, in the case ofso-called divergent illumination of the scale without collimator optics,it may also be necessary to select active detector regions of thereference pulse signal detector regions G_(REF)n for generating areference pulse signal that do not exactly reproduce the structure ofthe reference marking field in the detector plane. In such a case, thetargeted adaptation of aperiodic structures is done both for thereference marking field and for structures on the detector side. It mayequally be necessary in the case of divergent illumination to select thereference pulse signal detector regions such that they correspond to anenlarged picture of the reference marking field on the scale.Nevertheless, even in the case of aperiodic structures in the referencemarking field, as in the case of the aperiodic location of activedetector regions for generating a reference pulse signal, a definedcorrelation or dependency exists between how the reference marking fieldis embodied and the selection of reference pulse signal detector regionsfor generating a reference pulse signal. With respect to how suitablearrangements for generating reference pulse signals are embodied in thecase of divergent illumination, German Patent Disclosure DE 197 26 936of the present Applicant is hereby referred to as well.

To generate the incremental signals INC₀ and INC₉₀ phase-offset by 90°with the aid of the scanning unit of the present invention, it is nowprovided in the exemplary embodiment shown in FIG. 3a that the k^(th)active detector regions D1-D44 (k=1 . . . 4) of the incremental signaldetector regions G_(INC) 1-G_(INC) 7 are each suitably interconnected orin correct phase; as noted above, these detector regions are usedprimarily to generate the phase-offset incremental signals INC₀ andINC₉₀. In the case where k=1, these are the active detector regions D1,D5, D9, D17, D25, D29 and D41, which are electrically conductivelyconnected to one another and are connected to a first input of a firstsummation element SUM1. Upstream of the various summation elementsSUM1-SUM4, it is also possible for preamplifiers or current-voltageconverters—not shown—to be disposed. The in-phase signals of the firstactive detector regions D13, D21, D33 and D37 (k=1) of those groups offour that belong to the aforementioned reference pulse signal detectorregions G_(REF)n and are used primarily to generate the reference pulsesignal REF are connected to the second input of the first summationelement SUM1.

To generate the incremental signal INC₀, the summation signal present atthe output of the first summation element SUM1 is connected to the firstinput of a subtractor DIF1. The signal components, added together viathe summation element SUM3, of those third (k=3) active detector regionsD3, D7, D11, D15, D19, D23, D27, D31, D35, D39 and D43 of each group offour that generate scanning signals which are phase-offset by 180° fromthe output signals of the first active detector regions (k=1) of eachgroup of four are connected to the second input of the subtractor DIF1.At the output of the subtractor DIF1, the desired first incrementalsignal INC₀, free of direct current components, is then available.

In an entirely analogous way, by the interconnection shown of the secondand fourth active detector regions (k=2, 4) of each group of four and bythe processing of the individual signal components via the summation andsubtractor SUM2, SUM4 and DIF2, the second incremental signal INC₉₀ isalso generated, which has a phase-offset of 90° from the firstincremental signal INC₀.

For forming the reference pulse signal REF, on the one hand now then^(th) active detector regions (k=1, 2, 3, 4) of each group of four ofthe reference pulse signal detector regions G_(REF) 1-G_(REF) 4 thatdepending on the selected structure of the reference marking field 7 onthe scale are used primarily to generate the reference pulse signal REFare now electrically conductively connected to one another. To that end,in the case where k=1, for instance, the active detector regions D13,D21, D33 and D37 of the fourth, sixth, ninth and tenth reference pulsesignal detector regions G_(REF) 1-G_(REF) 4, beginning at the left, areconnected to one another; the same is done analogously for the activedetector regions where k=2 through 4. The combined signal components ofthese selected detector regions are then added up via a summationelement SUM6, and the resultant summation signal is applied to the firstinput of a subtractor DIF3. A reference pulse signal which is generatedfrom all the signal components summed up and sent from the activedetector regions D1-D44 is now present at the second input of thissubtractor DIF3 and in the final analysis is equivalent to a so-calledequa1-light signal. The result at the output of the subtractor DIF3 isthen the desired reference pulse signal REF.

As an alternative to this variant, a signal that results solely fromadding together the signal components of the incremental signal detectorregions could also be applied to the second input of the subtractorDIF3. As the reference signal, accordingly instead of an equal-lightsignal with an always-constant signal level, there would be a so-calledphase-opposition signal.

The incremental signals generated according to the present invention,that is, INC₀, INC₉₀, are again shown in FIG. 3b; this also shows thereference pulse signal REF at the reference position x_(REF). As canalso be seen from this merely schematic illustration, on the basis ofthe inventive-provisions explained here, in the three-dimensional regionof the reference position x_(REF), not only the reference pulse signalREF but also the incremental signals INC₀, INC₉₀ can be generated.

As can also be seen from FIG. 3b, the reference pulse signal REF now nolonger has any modulated signal component with the period of theincremental signals INC₀, INC₉₀. In the second exemplary embodimentdescribed, this unwanted signal component of the reference pulse signalREF is filtered, in that to generate the reference pulse signal REF foreach subscript value k=1, 2, 3, 4, the same number of active detectorregions within the reference pulse signal detector regions G_(REF)1-G_(REF) 4 is always selected, which in turn generate signals with allthe existing phase relationships. The sum of equa1-magnitude signals inall four phase relationships then no longer contains any periodic signalcomponent originating from the scanning of the incremental signal. Inthis respect there is no need for all the phase relationships to beadded up within one reference pulse signal detector region. Instead, itis equally sufficient in all of the reference pulse signal detectorregions for each phase relationship to add up approximately the samenumber of detector regions.

With respect to filtering the incremental signal component from thereference pulse signal, the various provisions disclosed in Germanpatent application 197 34 136.5 of the present Applicant should also bereferred to.

A third embodiment of the scanning unit of the present invention isshown in FIG. 4a in conjunction with part of the scale scanned with it.

A reference marking field 70, again integrated with the scale, isdisposed in the incremental graduation track 90 having the incrementalgraduation 80. With respect to the embodiment of the reference markingfield 70, a slightly different variant has been selected in thisexemplary embodiment. In the reference marking field 70, only threereference marking field subregions 70.1, 70.7 and 70.19 are opaque, in adeparture from the periodic arrangement of transparent and opaquesubregions.

The detector system 406 shown again includes a number of identicaldetector regions D401-D428, which are disposed adjacent one another inthe measuring direction x and are utilized to generate the incrementalsignals INC₀, INC₉₀ and also to generate the reference pulse signal REF.The identically embodied detector regions D401-D428 each have a widthb=TP/2 in the measuring direction x. The spacing of adjacent detectorregions is selected as d=TP/4; that is, the raster spacing r=3TP/4.

In the preceding exemplary embodiments, certain reference pulse signaldetector regions have been selected from the existing detector regionsas a function of the embodiment of the reference marking field 7 on thescale. The detector regions D409, D410, D413, D414, D421 and D422 serveas reference pulse signal detector regions for generating a referencepulse signal REF at a defined reference position. The disposition orselection of reference pulse signal detector regions is made as afunction of the location of those subregions 70.1, 70.7 and 70.19 thatdisturb the periodicity of the scanned structure in the referencemarking field 70 on the scale.

The remaining detector regions of the detector system 406 again functionas incremental signal detector regions, which are used primarily togenerate the incremental signals INC₀, INC₉₀. These include the detectorregions D401-D408, D411-D412, D415-D420, and D423-D428.

The exemplary embodiment shown in FIG. 4a now differs essentially in twopoints from the preceding exemplary embodiment of the scanning unit ofthe invention. The variant of FIG. 3a made a so-called single-fieldscanning possible, in which all the signal components for generatingincremental signals and reference pulse signals originated in the samegraduation period of the scale; in the exemplary embodiment of FIG. 4a,conversely, a so-called Vernier scanning is realized. It is also in themanner of filtration of the unwanted incremental signal component fromthe reference pulse signal that differs in the variant of FIG. 4acompared with the exemplary embodiment of FIG. 3a, where this was doneby interconnecting all the detector regions having the subscripts k=1through 4 of the reference pulse signal detector regions.

In the exemplary embodiment of FIG. 4a, on the one hand a so-calledVernier scanning is now realized. The successive disposition of thevarious detector regions D401-D428 accordingly differs from thearrangement described in conjunction with FIG. 2a, and in particular thephase relationships of the signals from the individual adjacent detectorregions D401-D428 differ from one another. A Vernier scanning isunderstood in general to mean scanning of a periodic scale structureusing a periodic scanning structure; the center spacings of in-phasedetector regions are greater than the period of the pattern of intensitygenerated by the scale in the detector plane. The periodicities of thescale structure and the scanning structure accordingly differ from oneanother.

Secondly, the exemplary embodiment of FIG. 4a shows a further variantfor filtering the modulated periodic incremental signal component fromthe reference pulse signal REF, as will be explained hereinafter.

To generate the incremental signals INC₀, INC₉₀, in FIG. 4a variousincremental signal detector regions are interconnected that generatein-phase signal components in the scanning process. Two of thecorresponding four signals with phase relationships each differing by90° from one another reach the inputs of summation elements SUM401,SUM402 in the exemplary embodiment shown, and to each of these summationelements, via the second input, a respective signal component isdelivered that originates in the interconnected reference pulse signaldetector regions D409, D410, D413, D414, D421, D422, each having thesame phase relationship as the incremental signal.

It is understood that as an alternative to the exemplary embodimentshown, instead of only two phase relationships, other combinations, suchas one or three phase relationships, and so forth, can be used togenerate reference pulse signal.

The signals present at the outputs of the summation elements SUM401,SUM402 are finally, like the remaining incremental signal components,delivered in the manner shown to two subtractors DIF401 and DIF402, atwhose outputs the incremental signals INC₀, INC₉₀ free of direct currentare present.

To generate a filtered reference pulse signal, it is provided that theoutputs of the selected reference pulse signal detector regions D409,D410, D413, D414, D421, D422, each having the same phase relationship,be interconnected, and that the two out-of-phase signal components beadded up via the summation element SUM404. Accordingly the outputsignals of the reference pulse signal detector regions D409, D413 andD421 that have the phase relationship of 0° are connected to oneanother; this is analogously done for the reference pulse signaldetector regions D410, D414 and D422 that each have the phaserelationship of 270°. The first reference pulse signal component RTpresent at the output of the summation element SUM404 is delivered to afirst input of a subtractor DIF403. A second reference pulse signalcomponent RGT is present at the second input of the subtractor DIF403.The second reference pulse signal component RGT has a phaserelationship, particularly in the region adjacent to the referenceposition x_(REF), that makes it possible, by forming the differencebetween the two signal components RT, RGT, to eliminate or filter outthe unwanted incremental signal component from the reference pulsesignal REF. The phase relationship or phase depth of the signalcomponents that is required for this can be adjusted suitably by meansof the suitable interconnection or amplification of the signalcomponents having the same phase relationship, or of all the signalcomponents. Forming the difference between the two reference pulsesignal components RT, RGT is done with the aid of the aforementioneddifference forming element DIF403. At its output, finally, the desiredreference pulse signal REF is present, which adjacent to the referenceposition x_(REF) no longer has any modulated incremental signalcomponent.

To generate the second reference pulse signal component RGT, it isprovided in the second exemplary embodiment of FIG. 4a that theout-of-phase signals present at the outputs of the two summationelements SUM401, SUM402 be added up with the aid of a further summationelement SUM403. The signal RGT present at the output of the summationelement SUM403 is then delivered as described to the second input of thesubtractor DIF403.

To make an adaptation of the signal level of those signals that aredelivered to the subtractor DIF403, an amplifier element AMP401 with again that is selected in a defined way or is adjustable is provideddownstream of the summation element SUM404 in the exemplary embodimentshown. By the way of this amplifier element, the signal levels of thesignals RT and RGT can be selected suitably, which is important in thisexemplary embodiment in the sense that to form the two signals RT andRGT, a different number of detector regions is used in each case, anddifferent signal intensities thus result. It is understood that afurther amplifier element can also be disposed between the summationelement SUM403 and the subtractor DIF403. It would also be possible, asalready noted above, to perform an electronic addition of a suitableoffset to one of the two signal components.

The signal shape of the two reference pulse signal components RT, RGTgenerated in the region of the reference position x_(REF) and thereference pulse signal REF resulting finally in the difference formingare shown in FIGS. 4a-4 c. In FIG. 4c, a trigger threshold TS is alsoshown, with the aid of which a square wave signal can be generated in aknown manner from the reference pulse signal REF via a triggerelement—not shown.

To eliminate the unwanted incremental signal component from thereference pulse signal REF, it is accordingly provided in thisembodiment that at least two reference pulse signal components begenerated, with a relative phase relationship such that by combining thedifferent reference pulse signal components, in particular adjacent tothe reference position, this periodic incremental signal component canbe eliminated. Depending on the phase relationship of the referencepulse signal components generated, this can be done by addition or bydifference forming, and so forth.

Accordingly, it is understood that along with the variant arrangementshown, other possibilities of performing this kind of elimination of theunwanted incremental signal component from the reference pulse signalREF are possible by combining the most various reference pulse signalcomponents generated.

A still more extensive feature of the third exemplary embodiment isshown in FIG. 5, on the basis of which a fourth exemplary of thescanning unit of the invention will be explained.

The construction of the scanner arrangement 506 shown is similar to thepreceding exemplary embodiment. Of the detector regions D501-D548, onceagain certain detector regions act as reference pulse signal detectorregions D517, D518, D525, D526, D537, D538, D541, D542. These regionswere newly selected as a function of the selected embodiment of thereference marking field 7 on the scale. The remaining detector regionsof the detector system 506 function as incremental signal detectorregions.

In principle, the generation of the two incremental signals INC₀, INC₉₀is done as in the preceding exemplary embodiment, which is thus merelyreferred to at this point.

The exemplary embodiment of FIG. 5 is now distinguished from the variantdescribed above in that an alternative generation of the variousreference pulse signal components RT, RGT that are finally used to formthe reference pulse signal REF is provided. Analogous to the terminologyof the preceding exemplary embodiment, another variant for generatingthe second reference pulse signal component RGT is provided inparticular, which is supplied along with the first reference pulsesignal component RT to the subtractor DIF503. For generating the secondreference pulse signal component RGT, it is now provided that only twodifferent phase relationships of selected incremental signal detectorregions be added together via the summation element SUM505 and deliveredto the second input of the subtractor DIF503. The selection of suitableincremental signal detector regions is done here with a view to the bestpossible suppression of interfering signal peaks of the reference pulsesignal REF outside the reference position x_(REF). In order now toassure the elimination of the unwanted incremental signal component fromthe reference pulse signal REF, amplifier elements AMP1-AMP7 aredisposed in the signal connecting lines of all the detector regionsconnected in phase; each of these amplifier elements has a gaincharacteristic that can be adjusted in a defined way. The gaincharacteristic of these amplifier elements AMP1-AMP7 is adjusted suchthat particularly in the difference forming from the two reference pulsesignal components via the subtractor DIF503, the result is that theunwanted incremental signal component is eliminated from the referencepulse signal REF. This means that it is accordingly assured in this waythat in the region adjacent to the reference position x_(REF), thevarious reference pulse signal components RT, RGT have substantially thesame amplitudes.

A further, sixth embodiment of the scanning unit of the presentinvention will be described briefly in conjunction with FIG. 6, whichagain shows a plan view on the detector plane of a structured detectorsystem 606 with various signal processing building blocks.

The structured detector system 606 again includes a number of detectorregions D600-D631, which are disposed adjacent one another in themeasuring a direction x. As already explained for the second exemplaryembodiment, this can be done for instance by means of suitablystructuring a semiconductor substrate. Unlike the previous exemplaryembodiments, to generate the reference pulse signal REF and phase-offsetincremental signals INC₀, INC₉₀, not only are active detector regionsD600-D631 that are all embodied identically provided. Instead, the fourreference pulse signal detector regions D612, D617, D626 and D627, whichare utilized to generate the reference pulse signal REF, have adifferent form from the identical remaining incremental signal detectorregions D600-D611, D613-D616, D618-D625, D628-D631, which are used togenerate the incremental signals INC₀, INC₉₀. The form of the referencepulse signal detector regions D612, D617, D626 and D627 has beenselected here such that by way of them, optical filtering of the signalcomponent, modulated to the reference pulse signal REF, with the periodof the incremental signals INC₀, INC₉₀ results. As already described inthe parallel application DE 197 34 136.5 of the present Applicant,individual subregions of the reference pulse signal subregions D612,D617, D626 and D627 are offset from one another, perpendicular to themeasuring direction x, by one-half of a graduation period of the scalegraduation scanned. With this kind of embodiment of the reference pulsesignal detector regions D612, D617, D626 and D627, the desired filteringis obtained; that is, the incremental signal components modulated inphase opposition are deleted from the reference pulse signal REF.

In principle, it is understood that other geometric shapes of thereference pulse signal detector regions can be selected so as to achievethe desired filtering.

In this embodiment, to generate the reference pulse signal REF, theoutput signals of the reference pulse signal detector regions D612,D617, D626 and D627 are delivered to a first input of a subtractorDIF603. At the second input of the subtractor DIF603 there is a signalthat results from the adding up of the output signals of all theincremental signal detector regions D600-D611, D613-616, D618-D625,D628-D631 via the summation element SUM.

The phase-offset incremental signals INC₀, INC₉₀ are generated inprinciple analogously to the above exemplary embodiments. In each caseit is provided that the in-phase output signals of the incrementalsignal detector regions be connected to one another and delivered in theknown manner to two subtractors DIF601 and DIF602. At the output of thetwo subtractors DIF601 and DIF602, the two phase-offset incrementalsignals INC₀, INC₉₀ are then present for further processing.

Further options relating to the advantageous embodiment or modificationof the scanning unit of the present invention will be described belowwith the aid of FIGS. 7a-7 d.

The intent is first to make it quite clear that within the scope of thepresent invention, it is not at all compulsory always to use groups offour active detector regions within reference pulse signal detectorregions for generating a reference pulse signal; the three-dimensionallocation in the structured detector system has a correlation with thestructure to be scanned of the reference marking field.

If on the scale 32 shown in FIG. 7a, for instance, an aperiodicstructure of the reference marking field 37 with transparent and opaquesubregions in the incremental graduation track 39 is selected, then theresult, even in the shadow-casting mode of such a system is adistribution of intensity at the reference position in the detectorplane, as shown in FIG. 7b. The reason for this is unavoidablediffraction effects.

If such a structure of the reference marking field 37, or the resultantintensity pattern in the detector plane, is to be optimally scannedoptically, then it is for instance also possible to use more than fouractive detector regions, connected with the correct phase, of astructured detector system. This is shown in FIG. 7c with five activedetector regions D35-D39, for example, of a detector system 36 that areused, suitably connected in correct phase, to generate the desiredreference pulse signal. The aforementioned filtration of the unwantedincremental signal component out of the reference pulse signal can againbe assured if the same number of detector regions per phase relationshipare connected to one another.

Depending on the selected structure of the reference marking field andthe resultant distribution of intensity in the detector plane at thereference position, it is accordingly possible to make a suitableselection of the number of active reference pulse signal detectorregions that serve, connected with the correct phase, to generate thereference pulse signal.

It will also be described in conjunction with FIG. 7d that it is alsopossible within the scope of the present invention for the activereference pulse signal detector regions D35′-D39′, which are usedprimarily to generate the reference pulse signal, not over the fullwidth of the incremental graduation track but rather to use only asubregion of the active detector regions D35′-D39′ to generate thescanning signals. To that end, the active detector regions selected forgenerating the reference pulse signal can approximately have differentlengths, as indicated in FIG. 7d for the detector regions D35′-D39′. Asan alternative to a variant of this kind, for the same purpose signalcomponents from identical active detector regions can also be amplifieddifferently.

In this way, in the event of divergent illumination, for instance, astill-optimized correlation between the aperiodic structures of thereference marking field on the scale and the likewise aperiodicallydistributed active detector regions for generating the reference pulsesignal can be attained or adjusted.

Within the scope of these last-mentioned provisions, it is alsopossible, within a structured detector system, to provide a certainnumber of active detector regions of equal length; certain activedetector regions, which are used primarily for instance to generate thereference pulse signal, are longitudinally divided into two subregions,however. While one subregion of a thus-divided active detector region isused according to the present invention to generate the reference pulsesignal and to generate at least one incremental signal, the secondsubregion can be used primarily to generate an incremental signal, forinstance, and so forth.

It can furthermore be provided that the active detector regions not berectangular, but instead to provide detector regions whose edge issinusoidal in the measuring direction, for instance.

The signals from detector regions with different phase relationshipsthat are used for generating a reference pulse signal can also beamplified differently, so as to perform an optimization of the width ofthe reference pulse signal in this way.

It is also possible for individual detector regions or all the detectorregions to be disposed at irregular intervals. In that way the harmoniccontent, for instance, of the incremental signals can be reduced, or theaforementioned filtering effect can be attained.

In addition, it is understood that the reference marking fieldintegrated with the incremental graduation track can be created, insteadof by a conversion of bright fields into dark fields, but convertingdark fields into bright fields.

It is furthermore possible to integrate the components of the wiringelectronics, or at least some of them, on a single detector chip.

Within the scope of the present invention, a great number andversatility of embodiment possibilities exist; that is, the provisionsdescribed above can, it is understood, be selected suitably and combinedin accordance with a given requirement.

The invention may be embodied in other forms than those specificallydisclosed herein without departing from its spirit or essentialcharacteristics. The described embodiments are to be considered in allrespects only as illustrative and not restrictive, and the scope of thepresent invention is commensurate with the appended claims rather thanthe foregoing description.

We claim:
 1. A scanning unit for an optical position measuring device,comprising: a detector system comprising: a first reference pulse signaldetector region disposed along a measuring direction; a second referencepulse signal detector region disposed along said measuring direction,wherein the relative disposition of the reference pulse signal detectorregions in said measuring direction is selected as a function of thestructuring of a reference marking field on a scale for generating areference pulse signal, and an incremental signal detector regiondisposed along said measuring direction and between said first andsecond reference pulse signal detector regions to generate at least oneincremental signal that is generated as a separate signal from saidreference pulse signal.
 2. The scanning unit of claim 1, wherein saiddetector system is embodied as a structured detector system, whichincludes a plurality of radiation-sensitive detector regions on a commonsemiconductor substrate.
 3. The scanning unit of claim 2, wherein saidstructured detector system has a plurality of radiation-sensitivedetector regions of identical form, which are disposed adjacent oneanother in said measuring direction.
 4. The scanning unit of claim 1,wherein said incremental signal detector region comprises a plurality ofindividual detector regions disposed adjacent one another, whichgenerate output signals each with a different phase relationship.
 5. Thescanning unit of claim 1, wherein said first reference pulse signaldetector region comprises a plurality of individual detector regionsdisposed adjacent one another, which generate output signals with adifferent phase relationship.
 6. A scanning unit for an optical positionmeasuring device, comprising: a detector system comprising: a firstreference pulse signal detector region disposed along a measuringdirection; a second reference pulse signal detector region disposedalong said measuring direction, wherein the relative disposition of thereference pulse signal detector regions in said measuring direction isselected as a function of the structuring of a reference marking fieldon a scale for generating a reference pulse signal; an incrementalsignal detector region disposed along said measuring direction andbetween said first and second reference pulse signal detector regions togenerate at least one incremental signal; and a subtractor, to one inputof which output signals of said first and second reference pulse signaldetector regions are present, while at a second input of said subtractora reference signal is present.
 7. A scanning unit for an opticalposition measuring device, comprising: a detector system comprising: afirst reference pulse signal detector region disposed along a measuringdirection; a second reference pulse signal detector region disposedalong said measuring direction, wherein the relative disposition of thereference pulse signal detector regions in said measuring direction isselected as a function of the structuring of a reference marking fieldon a scale for generating a reference pulse signal; and an incrementalsignal detector region disposed along said measuring direction andbetween said first and second reference pulse signal detector regions togenerate at least one incremental signal, wherein said first and secondreference pulse signal detector regions and said incremental signaldetector region are interconnected such that a filtration of a periodicincremental signal component at said reference pulse signal results. 8.The scanning unit of claim 6, wherein said first and second referencepulse signal detector regions each include four adjacent detectorregions that generate output signals phase-displaced by 90°, and whereinsaid adjacent detector regions comprise detector regions that generatein-phase output signals and are connected to one another, and saidin-phase output signals are delivered to a summation element thatgenerates an output reference signal that is directed to an input of thesubtractor.
 9. The scanning unit of claim 7, wherein said first andsecond reference pulse signal detector regions each include fouradjacent detector regions that generate output signals phase-displacedby 90°, and wherein said adjacent detector regions comprise detectorregions that generate in-phase output signals and are connected to oneanother, and said in-phase output signals are delivered to a summationelement that generates an output reference signal that is directed to aninput of the subtractor.
 10. The scanning unit of claim 7, whereinvarious reference pulse signal components can be generated, on the basisof whose combination the periodic incremental signal component can beeliminated from the reference pulse signal.
 11. The scanning unit ofclaim 10, wherein said reference signal is formed of added-upincremental signal components generated at least in part by saidincremental signal detector region.
 12. The scanning unit of claim 10,further comprising amplifier elements that adjust the amplitudes ofsignals generated by said first and second incremental signal pulsesignal detector regions and said reference pulse signal detector region.13. A scanning unit for an optical position measuring device,comprising: a detector system comprising: a first reference pulse signaldetector region disposed along a measuring direction; a second referencepulse signal detector region disposed along said measuring direction,wherein the relative disposition of the reference pulse signal detectorregions in said measuring direction is selected as a function of thestructuring of a reference marking field on a scale for generating areference pulse signal; and an incremental signal detector regiondisposed along said measuring direction and between said first andsecond reference pulse signal detector regions to generate at least oneincremental signal, wherein at least two of said first and secondincremental signal pulse signal detector regions and said referencepulse signal detector region are used both to generate a reference pulsesignal and to generate an incremental signal.
 14. An optical positionmeasuring device for determining the relative position of a first partand a second part that are movable relative to one another, said devicecomprising: a scale attached to said first part, wherein said scalecomprises a reference marking field that is integrated with anincremental graduation track; a scanning unit movable relative to saidscale and comprising: a detector system comprising: a first referencepulse signal detector region disposed along a measuring direction; asecond reference pulse signal detector region disposed along saidmeasuring direction, wherein the relative disposition of the referencepulse signal detector regions in said measuring direction is selected asa function of the structuring of said reference marking field forgenerating a reference pulse signal at a defined reference position ofsaid scale; and an incremental signal detector region disposed alongsaid measuring direction and between said first and second referencepulse signal detector regions to generate at least one incrementalsignal that is generated as a separate signal from said reference pulsesignal.
 15. The optical position measuring device of claim 14, whereinsaid detector system is embodied as a structured detector system, whichincludes a plurality of radiation-sensitive detector regions on a commonsemiconductor substrate.
 16. The optical position measuring device ofclaim 15, wherein said structured detector system has a plurality ofradiation-sensitive detector regions of identical form, which aredisposed adjacent one another in said measuring direction.
 17. Theoptical position measuring device of claim 14, wherein said incrementalsignal detector region comprises a plurality of individual detectorregions disposed adjacent one another, which generate output signalseach with a different phase relationship.
 18. The optical positionmeasuring device of claim 14, wherein said first reference pulse signaldetector region comprises a plurality of individual detector regionsdisposed adjacent one another, which generate output signals with adifferent phase relationship.
 19. An optical position measuring devicefor determining the relative position of a first part and a second partthat are movable relative to one another, said device comprising: ascale attached to said first part, wherein said scale comprises areference marking field that is integrated with an incrementalgraduation track; a scanning unit movable relative to said scale andcomprising: a detector system comprising: a first reference pulse signaldetector region disposed along a measuring direction; a second referencepulse signal detector region disposed along said measuring direction,wherein the relative disposition of the reference pulse signal detectorregions in said measuring direction is selected as a function of thestructuring of said reference marking field for generating a referencepulse signal at a defined reference position of said scale; anincremental signal detector region disposed along said measuringdirection and between said first and second reference pulse signaldetector regions to generate at least one incremental signal; asubtractor, to one input of which output signals of said first andsecond reference pulse signal detector regions are present, while at asecond input of said subtractor a reference signal is present.
 20. Anoptical position measuring device for determining the relative positionof a first part and a second part that are movable relative to oneanother, said device comprising: a scale attached to said first part,wherein said scale comprises a reference marking field that isintegrated with an incremental graduation track; a scanning unit movablerelative to said scale and comprising: a detector system comprising: afirst reference pulse signal detector region disposed along a measuringdirection; a second reference pulse signal detector region disposedalong said measuring direction, wherein the relative disposition of thereference pulse signal detector regions in said measuring direction isselected as a function of the structuring of said reference markingfield for generating a reference pulse signal at a defined referenceposition of said scale; an incremental signal detector region disposedalong said measuring direction and between said first and secondreference pulse signal detector regions to generate at least oneincremental signal, wherein said first and second reference pulse signaldetector regions and said incremental signal detector region areinterconnected such that a filtration of a periodic incremental signalcomponent at said reference pulse signal results.
 21. The opticalposition measuring device of claim 19, wherein said first and secondreference pulse signal detector regions each include four adjacentdetector regions that generate output signals phase-displaced by 90°,and wherein said adjacent detector regions comprise detector regionsthat generate in-phase output signals and are connected to one another,and said in-phase output signals are delivered to a summation elementthat generates an output reference signal that is directed to an inputof the subtractor.
 22. The optical position measuring device of claim20, wherein said first and second reference pulse signal detectorregions each include four adjacent detector regions that generate outputsignals phase-displaced by 90°, and wherein said adjacent detectorregions comprise detector regions that generate in-phase output signalsand are connected to one another, and said in-phase output signals aredelivered to a summation element that generates an output referencesignal that is directed to an input of the subtractor.
 23. The opticalposition measuring device of claim 20, wherein various reference pulsesignal components can be generated, on the basis of whose combinationthe periodic incremental signal component can be eliminated from thereference pulse signal.
 24. The optical position measuring device ofclaim 23, wherein said reference signal is formed of added-upincremental signal components generated at least in part by saidincremental signal detector region.
 25. The optical position measuringdevice of claim 23, further comprising amplifier elements that adjustthe amplitudes of signals generated by said first and second incrementalsignal pulse signal detector regions and said reference pulse signaldetector region.
 26. The optical position measuring device of claim 14,wherein at least two of said first and second incremental signal pulsesignal detector regions and said reference pulse signal detector regionare used both to generate a reference pulse signal and to generate anincremental signal.
 27. An optical position measuring device fordetermining the relative position of a first part and a second part thatare movable relative to one another, said device comprising: a scaleattached to said first part, wherein said scale comprises a referencemarking field that is integrated with an incremental graduation track; ascanning unit movable relative to said scale and comprising: a detectorsystem comprising: a first reference pulse signal detector regiondisposed along a measuring direction; a second reference pulse signaldetector region disposed along said measuring direction, wherein therelative disposition of the reference pulse signal detector regions insaid measuring direction is selected as a function of the structuring ofsaid reference marking field for generating a reference pulse signal ata defined reference position of said scale, and an incremental signaldetector region disposed along said measuring direction and between saidfirst and second reference pulse signal detector regions to generate atleast one incremental signal that is generated as a separate signal fromsaid reference pulse signal.
 28. The scanning unit of claim 1, wherein asubtractor is provided, to one input of which output signals of saidfirst and second reference pulse signal detector regions are present,while at a second input of said subtractor a reference signal ispresent.
 29. The scanning unit of claim 1, wherein said first and secondreference pulse signal detector regions and said incremental signaldetector region are interconnected such that a filtration of a periodicincremental signal component at said reference pulse signal results. 30.The scanning unit of claim 28, wherein said first and second referencepulse signal detector regions each include four adjacent detectorregions that generate output signals phase-displaced by 90°, and whereinsaid adjacent detector regions comprise detector regions that generatein-phase output signals and are connected to one another, and saidin-phase output signals are delivered to a summation element thatgenerates an output reference signal that is directed to an input of thesubtractor.
 31. The scanning unit of claim 29, wherein said first andsecond reference pulse signal detector regions each include fouradjacent detector regions that generate output signals phase-displacedby 90°, and wherein said adjacent detector regions comprise detectorregions that generate in-phase output signals and are connected to oneanother, and said in-phase output signals are delivered to a summationelement that generates an output reference signal that is directed to aninput of the subtractor.
 32. The scanning unit of claim 29, whereinvarious reference pulse signal components can be generated, on the basisof whose combination the periodic incremental signal component can beeliminated from the reference pulse signal.
 33. The scanning unit ofclaim 32, wherein said reference signal is formed of added-upincremental signal components generated at least in part by saidincremental signal detector region.
 34. The scanning unit of claim 32,further comprising amplifier elements that adjust the amplitudes ofsignals generated by said first and second incremental signal pulsesignal detector regions and said reference pulse signal detector region.35. The scanning unit of claim 1, wherein at least two of said first andsecond incremental signal pulse signal detector regions and saidreference pulse signal detector region are used both to generate areference pulse signal and to generate an incremental signal.
 36. Theoptical position measuring device of claim 14, wherein a subtractor isprovided, to one input of which output signals of said first and secondreference pulse signal detector regions are present, while at a secondinput of said subtractor a reference signal is present.
 37. The opticalposition measuring device of claim 14, wherein said first and secondreference pulse signal detector regions and said incremental signaldetector region are interconnected such that a filtration of a periodicincremental signal component at said reference pulse signal results. 38.The optical position measuring device of claim 36, wherein said firstand second reference pulse signal detector regions each include fouradjacent detector regions that generate output signals phase-displacedby 90°, and wherein said adjacent detector regions comprise detectorregions that generate in-phase output signals and are connected to oneanother, and said in-phase output signals are delivered to a summationelement that generates an output reference signal that is directed to aninput of the subtractor.
 39. The optical position measuring device ofclaim 37, wherein said first and second reference pulse signal detectorregions each include four adjacent detector regions that generate outputsignals phase-displaced by 90°, and wherein said adjacent detectorregions comprise detector regions that generate in-phase output signalsand are connected to one another, and said in-phase output signals aredelivered to a summation element that generates an output referencesignal that is directed to an input of the subtractor.
 40. The opticalposition measuring device of claim 37, wherein various reference pulsesignal components can be generated, on the basis of whose combinationthe periodic incremental signal component can be eliminated from thereference pulse signal.
 41. The optical position measuring device ofclaim 40, wherein said reference signal is formed of added-upincremental signal components generated at least in part by saidincremental signal detector region.
 42. The optical position measuringdevice of claim 40, further comprising amplifier elements that adjustthe amplitudes of signals generated by said first and second incrementalsignal pulse signal detector regions and said reference pulse signaldetector region.